Limit stop device for the opening of sun curtains

Abstract

 The limit stop device for the opening of sun curtains exploits the tendency of cross frontal bar (5) urged by arms (6,7) to unroll the curtain from roller (2) on which it is wound.
The device consists of a ratchet mechanism (10) comprising a cylinder (12) provided with teeth (14) and inside which turns a pin (20) having spring teeth (30).
The rotation of pin (20) in one direction, disen­gages teeth (30) from the teeth (14) of cylinder (12), thereby allowing the curtain to unroll in steps only up to the maximum possible opening while in the opposite direction it allows re­winding of the curtain on roller (2)

Description

[0001] This specification relates to a limit stop device for the opening of sun curtains. The sun curtains are wound on a roller secured to a wall and which is caused to rotate in one direction or the opposite direction to unwind and re-wind the curtain.

[0002] The end of the curtain is secured to a frontal rod supported by two articulated arms fitted with springs and which tend elastically to move the rod away from his housing applied on the wall in order to keep the curtain constantly stretched.

[0003] When the arms are extended to their maximum limit, and if the user is not careful, in continuing to turn the roller, the curtain will first loosen and may, immediately, after, rewind itself on the roller in the opposite direction and this may damage the curtain, and prevent a correct gripping of the frontal rod on the housing.

[0004] To avoid this drawback, a greater length than necessary of curtain normally is wound on the roller, corresponding for example to two or three turns of the roller, but this expe­dient simply increases costs, without ensuring a good result.

[0005] The purpose of the invention is to provide a device apt to interrupt the unwinding of the curtain from the roller when the supporting arms of the frontal rod have reached their maximum extent of opening, so that even a distracted user will not be able to unwind the curtain more than necessary or rewind it in the opposite direction, which would damage both the curtain and the mechanism.

[0006] According to the invention, the device which exploit's the tendency of sun curtains to open under the action of sprung arms, is characterized by a ratchet mechanism fitted in the roller of the curtain; said mechanism consists of a small cylinder applied in the cavity of the roller and which is pro­vided with at least two fixed teeth projecting toward the axis of the cylinder itself and by a pin, rotatable within said cylinder, provided with sprung teeth apt to engage or not with the fixed teeth of the cylinder, depending on their rotating direction.

[0007] The mechanism is conceived so that by turning the pin in one direction, the oscillating teeth disengage from those of the cylinder, thereby enabling, thanks to the action exerted by the frontal rod, the opening by snap action of the curtain, which, in this way, cannot proceed beyond the maximum opening position, while turning the pin in the opposite direc­tion, the oscillating teeth engage with the small cylinder to re-wind the curtain.

[0008] An embodiment of the invention will now be described in more detail, by way of example, with reference to the drawings.

Fig. 1 is a view in transversal cross section of the sun curtain to which the device according to the invention is applied.

Fig. 2 is a longitudinal view, in cross section of the device, shown on a larger scale.

Fig. 3 is a transversal view in cross section, taken on line III-III of Fig. 2.

[0009] In Fig. 1 the sun curtain 1 is wound on a roller 2, inserted in a housing 3. End 4 of the curtain is secured to a cross frontal bar 5, sus­tained at both its ends, by arms 6 and 7 which tend to move away, elastically, frontal bar 5 from housing 3 by means of spring 8.

[0010] Device 10, according to the invention (see Figs. 2 and 3) consists of a cylinder 12 which, in the case illustrated in Fig. 3, is provided internally with three teeth 14 of rectan­gular cross section, integral with cylinder 12.

[0011] The center part of cylinder 12 is provided with a port 18 for a pin 20 restrained with a retaining ring inside the roll.

[0012] With pin 20 are integral a flange 22 inside cylinder 12 and an external flange 24 which practically is a closing cap for the cylinder itself. Flanges 22 and 24 retain, in the case shown in the drawings, three pins 26 on each of which is mounted an oscillating tooth 30 fitted with a spring 32 which tends to urge each tooth 30 elastically toward the exterior.

[0013] The oscillating teeth 30 have a substantially lenticular shaped cross section and a curved back 33. Teeth 30 are provided, at their free end, with an edge 34 apt to engage with the base of said rectangular teeth 14 crossing the internal surface 35 of cylinder 12.

[0014] The cylinder is secured in the hollow of roller 2 by shrinkage.

[0015] In the opposite part of device 10 (on the right hand side of fig. 2) pin 20 terminates with a square end on which a toothed wheel (not shown) is secured, said wheel being moved by an endless screw housed in box 50 and which is integral with a shaft 52 provided with an eyelet 54 to which can be applied a handle bar, apt to be rotated in one direction or the other by the user to unwind or rewind the curtain.

[0016] From the above description the operation of the device according to the invention is well evidenced.

[0017] In fact, considering Fig. 1 in the steady position shown on the drawing curtain 1, stretched elastically by arms 6,7 in the direction of arrow F cannot unwind itself from roller 2 as teeth 14 of cylinder 12 are engaged with oscillating teeth 30 these being in turn secured (through pin 20) to the endless screw gear which is in fact irreversible.

[0018] By turning shaft 52 (see fig. 2) so that the pin rotates clockwise, oscillating teeth 30 disengage from rectan­gular teeth 14 and the curtain can unwind in successive steps from roller 2.

[0019] When arms 6 and 7 are fully extended the traction exerted on the curtain ceases and consequently, oscillating teeth 30 continue turning idle.

[0020] In this way, even a distracted user will not be able to unwind the curtain from the roller beyond the position of maximum opening, and this avoids all possible drawbacks.

[0021] The length of curtain wound on the roller can thus be limited to the necessary extent, thereby affording a saving of cloth.

[0022] Also the rewinding of the curtain on roller 2 cannot be subject to errors, as the user, in turning the pin clockwise erroneously does not obtain any effect, while, if the rotating direction is reversed, oscillating teeth 30 engage with teeth 14 of cylinder 12 to permit rewinding of the curtain.

Claims

1) Limit stop device for sun curtain wound on a roller (2) and having their ends (4) secured to a frontal cross bar (5) urged outwardly by spring arms (6,7), characterized by a ratchet mechanism (10) fitted in one of the ends of roller (2) of the curtain, where said mechanism consists of a cylin­der (12) provided with integral rectangular cross section teeth (14) projecting towards the axis of the cylinder and by a pin (20) rotatable inside said cylinder and provided with elastically oscillating teeth (30) arranged in a manner such that by turning the pin in one direction, teeth (30) disengage teeth (14) from cylinder (12), thereby to permit a step by step opening movement of the curtain drawn by cross bar (5), and which stops in the maximum extended position of arms (6,7) or in any intermediate position, whilst by turning pin (20) in the opposite direction the elastically oscillating teeth (30) engage with teeth (14) of the cylinder to re-wind the curtain on roller (2).

2) Device according to claim 1, characterized in that pin (20) is rotatable in a port (18) in the center part of cylinder (12).

3) Device according to claims 1 and 2, characterized in that teeth (30) of the ratchet mechanism (10) oscillate on pins (26) the ends of which are secured on the one end to a flange (22) and on the other end to an outer flange (24) both inte­gral with pin (20) and of which flange (24) acts as a protect­ing cover for the opening of cylinder (12).

4) Device according to claim 3, characterized in that each of oscillating teeth (30) is elastically urged in a centrifugal direction by the action of a spring (32) the open ends of which rest, the one on pin (20) and the other on the surface of the tooth facing pin (20) itself.

5) Device according to claims 3 and 4 characterized in that oscillating teeth (30) have a lenticular shaped cross section so that, in the part corresponding to the end secured to pins (26), the thickness of tooth (30) is such as to enable its insertion tangentially with the surface of its back (33), substantially up to the mid part of rectangular teeth (14) so as to avoid scraping against the edges of said teeth (14).

Drawing